CN108869676B - Ball screw driving device - Google Patents

Abstract

A ball screw transmission device includes: a screw having a first free end and a second end, the second end being connectable to a driving device; and a screw nut coaxially at least partially surrounding the lead screw. A core element is formed by a plurality of balls that circulate in the gap between the screw and the screw nut. An extension sleeve is fixedly connected to the screw nut coaxially adjacent to the screw nut, and the extension sleeve and the screw nut are movable relative to the screw nut. A substantially circular support ring is arranged at the first free end on the outer circumference of the screw and serves as a shaft support between the screw and the extension sleeve. And the noise dampening effect is exerted by at least one integrated spring/damper element. The spring/damping element of the support ring is preferably a combination of at least one notch and a ring gap on the inner circumference of the support ring.

Description

Ball screw drive

Technical field

The invention relates to a ball screw drive, the screw of which has a noise-suppressing support device at the end.

Background technique

A rolling screw transmission device having balls as rolling elements is usually called a ball screw or a ball screw transmission device. Technically, a ball screw drive operates as a helical drive, the reduction or increase ratio of which is determined by the design dimensions of the screw, or more precisely by the thread path of the thread.

Ball screw drives are used in many technical applications, in particular in machine construction and in this case preferably in machine tools. However, ball screw drives are also increasingly used as longitudinal drives in areas where hydraulic systems have hitherto been customary, such as in extruders, injection molding machines and power steering systems.

Ball screw drives also play an increasingly important role in electromechanical and electrohydraulic braking systems. By means of this system, the brake pressure is to be built up independently of or in support of the driver's braking operation. In this case, braking signals from the driver or vehicle safety systems (eg collision warning, ABS sensor system) are evaluated electronically and transmitted to the electric motor as a system response. The rotational motion of the electric motor is converted into translational motion via a ball screw drive. This translational movement in turn can move the brake piston and thereby build up a brake pressure, in particular hydraulically, in one or more brake circuits or apply a braking effect directly (for example pressing a brake pad against a brake disc). superior).

Generally speaking, a ball screw transmission includes a lead screw and a lead screw nut surrounding the lead screw. The threads of the lead screw and lead screw nut are designed as running grooves for the balls. The balls circulating in the thread path between the spindle and the nut ideally (that is, without play) contact both sides of the thread at every point (Gothic running groove). The spindle nut (and rarely the spindle) is additionally equipped with a ball reversing device, which lifts the balls out of the running groove at a defined point and redirects them back at another point via a return channel. It is guided back into the thread path, thus achieving a closed ball circulation. The relative mobility of the screw and nut is achieved through circulating balls. At the same time, the balls serve as supports to transmit all the forces between the screw and the nut. Due to the low rolling friction in the ball screw drive, a mechanical efficiency of up to 95% is achieved. Depending on which component is driven and which component is linearly guided, the translation movement can be caused by the threaded spindle or by the nut.

Longer screws tend to vibrate during operation, especially when high axial movements of the screw nut are to be achieved, which usually require high rotational or drive speeds of the screw. Such vibrations may cause undesirable noise formation and result in increased wear. In current applications, this occurs more and more when the spindle can only be fixedly supported on one side.

Japanese Laid-Open Document JP 2013-19534A describes a linear drive device having a ball screw transmission device of the above type. A plastic element is mounted on the end of the threaded spindle guided in the sleeve as a supporting element, which helps to suppress deflection of the threaded spindle element. The plastic element has a plurality of grooves arranged on the periphery.

Contents of the invention

Starting from this prior art, the object of the present invention is to improve plastic components so that the noise suppression effect is achieved or improved.

The invention solves this problem by providing a spring or damping element integrated in the support ring, which spring or damping element is formed as a combination of at least one recess and a ring gap on the inner circumference of the support ring.

Such a ball screw transmission 10 includes a screw 12 with a first free end 16 and a second end 17 which can be connected to a drive device; and a screw nut 14 , which The nut coaxially surrounds the threaded spindle 12 at least partially, wherein a plurality of balls 26 circulate in the gap between the threaded spindle 12 and the threaded spindle nut 14 . The extension sleeve 15 adjoins the spindle nut 14 coaxially and is fixedly connected thereto. The extension sleeve together with the threaded spindle nut can therefore be moved relative to the threaded spindle 12 . Arranged on the first free end 16 on the outer circumference of the threaded spindle 12 are substantially circular support rings 18 , 30 , 50 , 70 which serve as a gap between the threaded spindle 12 and the extension sleeve 15 . The shaft supports and the support ring exerts a noise dampening effect via at least one integrated spring/damping element. In this case, the support ring is fastened to or on the first end of the threaded spindle such that the support ring can move with play, in particular rotate, but does not swivel. The lead screw slipped.

The spring/damping element of the support ring 30 , 50 , 70 here includes at least one recess 32 , 52 , 72 on the inner circumference of the support ring 30 , 50 , 70 and a ring gap 34 , 54 , 74 The combination. The spring/damping element is a structural feature of the support ring or a combination of individual technical features. Here, a recess is understood to mean a recess, a pocket, a cutout which weakens the material of the support ring at one point radially from the inside to the outside without completely interrupting the support ring. The recess can be designed as a straight slit or as a V- or U-shaped recess.

In contrast, the ring gaps 34 , 54 , 74 constitute a complete interruption of the support ring at one location. Preferably, the ring gap is designed such that at its narrowest point it lies between 0.1 mm and 0.8 mm (when mounted on the threaded spindle). In this case, the annular gaps 34 , 54 , 74 do not have to be designed as straight radial gaps, but can instead be designed with rounded edges or a wedge shape.

In another preferred embodiment, the ball screw drive 10 can have a spring/damping element supporting the ring 30 , 50 , 70 , which spring/damping element additionally includes at least one notch 36 , 56 on the outer circumference. 76. A notch here means an indentation, a recess, a pocket, which weakens the material of the support ring at one point radially from the outside inward without completely interrupting the support ring. The notches can be formed as straight slits or as V- or U-shaped recesses.

In a preferred embodiment, the recesses 36 , 56 , 76 on the outer circumference are formed as radially inwardly extending slots, the depth of which is the radial nominal ring of the support ring 30 , 50 , 70 measured from the outer circumference. 30%-60% of width.

Particularly preferably, the notches or gaps 36, 56, 76 have substantially the same width over their length. This corresponds to the design described above as a straight, uniform, essentially radial gap.

In a further development of the invention, (additional) gaps 59 , 79 are connected to the radially inner ends of the notches 56 , 76 , said gaps extending from the center points 60 , 80 of the support rings 50 , 70 to The external view essentially follows the course of a circular arc or a chord and forms an angle of 20° to 60°, especially an angle of 40° to 50°. In other words, the support ring has a substantially L-shaped notch in axial plan view, wherein the radial component is formed by the above-mentioned notch on the outer circumference, to which the notch or recess is connected at an angle of approximately right angles, The course of the notches or recesses can be described as arcs or chords of a circle. The length of the further gaps 59, 79 can best be described as the angle at which they are formed when viewed radially outward from the axial center point of the support ring.

In a further detailed embodiment of the invention, the further slots 59 , 79 can have a non-constant width over their extension and, in particular at their ends facing away from the recesses 56 , 76 , can exhibit a substantially narrow width of the slot wall. circular direction. In other words, the slot extending as a circular arc or a chord in the support ring has a drop-shaped expansion at its ends.

Through the L-shaped notch, the spring/damper element acquires a tongue-like shape. A block of material is defined by the notches 56 , 76 , by the further gaps 59 , 79 and by the outer circumference of the support ring 50 , 70 , which forms the pressing elements 58 , 78 with elastic tongues 57 , 77 .

In another preferred embodiment, the extrusion elements 58 , 78 can have a radius that deviates positively from the nominal outer diameter. This means that the nominal diameter of the support ring is slightly larger in the region of the elastic tongue. However, due to the elastic action of the tongue, the projection can be pressed radially inwards, so that the nominal outer diameter of the bearing ring is achieved under stress.

Preferably, the support rings 18, 30, 50, 70 can be formed in one piece from thermoplastic plastic.

In a further preferred embodiment, the spring/damper element of the bearing ring 90 of the ball screw drive 10 can additionally comprise at least one pressing element 98 on the outer circumference. This variant is shown in FIG. 5 . Instead of the recess 36 , a certain area or volume of material is provided on the outer circumference, which material acts as a pressing element. For this purpose, the pressing element 98 of the support ring 90 can be made of a material that is more elastic than the material of the remainder of the support ring 90 , in short a softer plastic. As also in one of the above-mentioned variants, the pressing element 98 can advantageously have a radius that deviates positively from the nominal outer diameter.

The support ring is mounted by pushing onto the first free end 16 of the threaded spindle. Fixing can be ensured by the flat, flange-like joint of the threaded spindle. The noise-suppressing effect of the bearing ring is furthermore achieved by the spring/damping element providing an elastic supporting effect between the extension sleeve 15 and the threaded spindle 12 . The extension sleeve and lead screw no longer vibrate independently but are supported relative to each other via a support ring. Vibrations of the lead screw or extension sleeve are reduced by the spring/damping element and are not easily transmitted to the mechanical components therein.

Description of the drawings

FIG. 1 shows a longitudinal sectional view of a ball screw drive according to the invention.

FIG. 2 shows an axial plan view (left), a cross-section (center) and a 3D view (right) of a support ring 30 as a component of a ball screw drive according to the invention in a simple first embodiment. .

FIG. 3 shows an axial plan view (left), a cross-sectional view (middle) and a 3D view (right) of a support ring 50 as a component of a ball screw drive according to the invention in a second, more complex embodiment. ).

FIG. 4 shows an axial plan view (left), a cross-sectional view (middle) and a 3D view (right) of a support ring 70 as a component of a ball screw drive according to the invention in a third embodiment.

FIG. 5 shows an axial plan view of the support ring 90 in a further developed embodiment.

Detailed ways

The invention will now be explained by way of example based on various embodiments with reference to the drawing.

FIG. 1 shows an axial longitudinal section through the ball screw drive 10 . The basic components are the threaded spindle 12 and the threaded spindle nut 14 which coaxially surrounds the threaded spindle 12 at least partially. The central longitudinal axis of the threaded spindle 12 simultaneously forms the system axis 28 . The spindle has a spiral, circumferential running groove 24 on the outside, similar to the thread path of a screw. The spindle nut 14 shows on its inner side an internal thread that is complementary to the spindle 12 and has a running groove that is also approximately (in cross section) half-shell-shaped. The gap between the spindle nut 14 and the spindle nut 12 is dimensioned in such a way that the balls 26 can circulate in the running groove and thus ensures an almost clearance-free relative movability of the spindle nut 12 and the spindle nut 14 . The figure shows two ball reversing devices 20 , 22 which ensure an infinite circulation of the balls. For this purpose, the balls are lifted out of the running groove at defined points by means of a lifting device (not shown here) and inserted again, offset by several pitches, into the gap between the spindle 12 and the spindle nut 14 . The two external ball counters shown here can in principle also be replaced by internal ball counters without affecting the idea of the invention.

The threaded spindle 12 has a first end 16 , which is depicted as a free end in FIG. 1 , and a second end 17 designed for connection to a drive. When the motor side is chosen as the stationary reference system, this means that when the threaded spindle 12 rotates, the threaded spindle nut moves axially. In this embodiment, the translational movement can be transmitted to a further adjusting or measuring element via an extension sleeve 15 which coaxially surrounds the spindle and is fixedly connected to the spindle nut 14 . In a technically equivalent embodiment, it goes without saying that the extension sleeve 15 and the spindle nut 14 can be produced in one piece. This difference has the following functional significance: the screw nut performs the function of a ball screw, whereas the extension sleeve 15 does not have an internal thread and is therefore also unable to accommodate balls. The support and guidance provided by the balls in the gap between the spindle nut 14 and the spindle 12 is therefore ineffective in the area of the elongated sleeve. However, it is of interest for both static and dynamic reasons to precisely define the relative position of these two components. Surprisingly, it turns out that a simple bearing ring on the first end 16 of the threaded spindle 12 is not sufficient; instead, the bearing ring can transmit vibrations generated during operation from one component to another. Therefore, the support ring 18 is modified in such a way that the support ring 18 serving as a shaft support between the threaded spindle 12 and the extension sleeve 15 acquires at least one integrated spring/damping element which exerts a noise dampening effect.

Therefore, FIG. 2 shows a simple first embodiment according to the invention. The spring/damping element of the support ring 30 includes a combination of at least one notch 32 and a ring gap 34 on the inner circumference of said support ring 30 . The same applies to Figures 2 to 4: a reference sign identified by an additional letter can exist multiple times. Therefore, Figure 1 has two notches 32a and 32b. The number of features shown and the figures are to be understood in this case only as an explanation and not as a limitation. In another embodiment, the spring/damping element 30 can additionally comprise at least one or more notches 36a, 36b, 36c on the outer circumference. The notches additionally assist spring or damping properties.

The gaps 36, 56, 75 can be configured differently. Figure 2 shows a notch-shaped notch 36 with a u- or v-shaped profile. The depth measured radially from the outer circumference towards the center point 40 may preferably be between 30% and 60% of the radial nominal ring width of the support ring (30, 50, 70). This data applies to all diagrams according to Figures 2, 3 and 4. Figures 3 and 4 show an embodiment of the notch as a slit extending radially inwardly on the outer circumference. This embodiment can also be used in the configuration according to FIG. 2 . In particular, notches are suitable as slits which have essentially the same width over their length.

Another variant of the spring/damping element continues with a design with slits 56 , 76 extending radially inwardly on the outer circumference. Further slots 59 , 79 are respectively arranged at the radially inner ends of the slots, which further slots extend substantially parallel to the outer circumference offset at an angle of approximately 90°. The further gap may be curved in the sense of extending strictly parallel to the periphery (arc of a circle) or linearly (chord of a circle) or in between these two extremes. The additional length of the further gap in radians is between 20° and 60°, preferably between 40° and 50°.

The further gaps 59 , 79 can be designed with a uniform width, as shown in FIG. 3 . However this is not mandatory. The width extension can be widened or narrowed during the extension, in particular the ends of the further slits 59 , 79 can be designed as semicircular or drop-shaped, similar to FIG. 4 . Such a substantially circular wall has advantages both in production and in its function as a spring element.

The essentially L-shaped design resulting from the two gaps 56 , 59 or 76 , 79 results in an elastically movable tongue 57 , 77 . The tongue can therefore also act radially outward as pressing elements 58 , 78 . This effect can be enhanced if the material thickness of the tongues 57 , 77 is slightly larger when viewed radially outward, ie if the outer diameter of the bearing ring 50 , 70 is slightly larger than the nominal value in this location.

The support ring can be produced in one piece from thermoplastic, preferably by injection molding.

In a preferred embodiment, the outer diameter of the support ring is 12.4 mm, the ring width is approximately 2.6 mm, and the depth is approximately 4 mm. However, these dimensions can be adapted to a large extent by enlarging or reducing without the teaching of the invention without losing the characteristics of the invention. In particular, the embodiments of the spring/damping elements (56, 57, 58, 59, 76, 77, 78, 79) shown in FIGS. 3 and 4 can also be arranged multiple times around the circumference of the support ring, depending on the design dimensions of the support ring. .

A further preferred embodiment of the support ring 90 is shown in FIG. 5 . The recesses 36 on the outer circumference of the support ring 90 as shown in FIG. 2 or the recesses formed similarly on the outer circumference are filled with a material that is more elastic than the material of the actual support ring. This prevents the ring from being weakened by material removal at this location in relation to the embodiment of FIG. 2 . At the same time, the elastic material achieves an elastic effect and therefore acts as a damping element. In a preferred variant, the material can project radially outwards in zone 98 beyond the outer circumference marked by the actual support ring 90 , which, similar to the variant of FIG. 4 , contributes to an enhanced damping effect. This variant is produced, for example, by assembly injection molding or multi-stage injection molding.

The features of the invention disclosed in the above description and in the drawings can be essential for the realization of the invention both individually and in any arbitrary, however technically meaningful or advantageous combination. The fact that a combination of features is not explicitly described does not mean that such combination is meaningless or unfeasible. Conversely, the common description of features does not imply that there is in each case a structural and/or functional connection between the features.

List of reference signs

10 Ball screw drive

12 lead screw

14 screw nut

15 extension sleeve

16 The first free end of the screw

17 Second end of lead screw

18 (round) support ring

26 balls

28 System Axis

30, 50, 70, 90 round support rings

32, 52, 72, 92 Notches on the inner circumference of the support ring

34, 54, 74, 94 ring clearance

36, 56, 76 gaps on the outer periphery

57, 77 elastic tongue

58, 78 extruded components

59, 79 additional (connected) gaps

98 Press element

40, 60, 80 Center point of support ring

a, b, c respectively represent the same element or feature if the element or feature

If present multiple times in an implementation form.

Claims (30)

1. A ball screw transmission device (10), the ball screw transmission device includes: - a lead screw (12) having a first free end (16) and a second end (17) connectable to a drive; and - a lead screw nut (14) coaxially at least partially surrounding the lead screw (12); and - a plurality of balls (26) circulating in the gap between the screw (12) and the screw nut (14); and - an extension sleeve (15) coaxially adjoining the screw nut (14) and fixedly connected to the screw nut, and which together with the screw nut can be positioned relative to the screw nut (14) Lead screw (12) movement; and - a substantially circular support ring (18, 30, 50, 70, 90) arranged on the outer circumference of the screw (12) at the first free end (16), said support ring serving as the Shaft support between screw (12) and extension sleeve (15), It is characterized in that the support ring (18, 30, 50, 70, 90) has an integrated damping element formed as at least one recess (32, 52, 72, 92) and the ring gap (34, 54, 74, 94) and play a role in suppressing noise. 2. Ball screw drive (10) according to claim 1, characterized in that the damping element of the bearing ring additionally includes at least one notch (36, 56, 76) on the outer circumference. 3. The ball screw transmission device (10) according to claim 2, characterized in that the notch (36, 56, 76) on the outer circumference is formed as a first gap extending radially inwards, The depth of the first gap is between 30% and 60% of the radial nominal ring width of the support ring, measured from the periphery. 4. Ball screw transmission (10) according to claim 2, characterized in that the notches have substantially the same width over their length. 5. Ball screw drive (10) according to one of claims 2 to 4, characterized in that the at least one notch is connected to the second gap (59, 79) at its radially inner end. ), the second gap substantially follows the direction of a circular arc or a circular chord and forms an angle of 20° to 60° when viewed outward from the center point (60, 80) of the support ring. 6. Ball screw transmission (10) according to claim 5, characterized in that the second gap (59, 79) has a non-constant width in its extension. 7. Ball screw drive (10) according to claim 5, characterized in that a block of material is defined by the notch, by the second gap (59, 79) and by the outer circumference of the support ring Extrusion elements (58, 78) are formed with elastic tongues (57, 77). 8. Ball screw drive (10) according to claim 7, characterized in that the extrusion element (58, 78) has a radius with a positive deviation from the nominal outer diameter. 9. Ball screw drive (10) according to one of claims 1 to 4, characterized in that the support ring is formed in one piece from thermoplastic plastic. 10. Ball screw drive (10) according to one of claims 1 to 4, characterized in that the damping element of the bearing ring additionally includes at least one pressing element (98) on the outer circumference. 11. Ball screw transmission (10) according to claim 10, characterized in that the at least one pressing element (98) of the support ring is made of a material that is more elastic than the remaining part of the support ring. material. 12. Ball screw transmission (10) according to claim 10, characterized in that the pressing element (98) has a radius with a positive deviation from the nominal outer diameter. 13. Ball screw transmission (10) according to claim 3, characterized in that the first gap has substantially the same width over its length. 14. The ball screw transmission device (10) according to claim 5, characterized in that the second gap substantially follows an arc or a chord when viewed outward from the center point (60, 80) of the support ring. trend and form an angle of 40° to 50°. 15. Ball screw drive (10) according to claim 6, characterized in that the end of the second slot facing away from the recess exhibits a substantially circular course of the slot wall. 16. A ball screw transmission device (10), the ball screw transmission device includes: - a lead screw (12) having a first free end (16) and a second end (17) connectable to a drive; and - a lead screw nut (14) coaxially at least partially surrounding the lead screw (12); and - a plurality of balls (26) circulating in the gap between the screw (12) and the screw nut (14); and - an extension sleeve (15) coaxially adjoining the screw nut (14) and fixedly connected to the screw nut, and which together with the screw nut can be positioned relative to the screw nut (14) Lead screw (12) movement; and - a substantially circular support ring (18, 30, 50, 70, 90) arranged on the outer circumference of the screw (12) at the first free end (16), said support ring serving as the Shaft support between screw (12) and extension sleeve (15), It is characterized in that the support ring (18, 30, 50, 70, 90) has an integrated spring element which is formed as at least one recess (32, 52, 72, 92) and the ring gap (34, 54, 74, 94) and play a role in suppressing noise. 17. Ball screw drive (10) according to claim 16, characterized in that the spring element of the bearing ring additionally includes at least one notch (36, 56, 76) on the outer circumference. 18. The ball screw transmission device (10) according to claim 17, characterized in that the notch (36, 56, 76) on the outer circumference is formed as a first gap extending radially inwards, the The depth of the first gap is between 30% and 60% of the radial nominal ring width of the support ring, measured from the periphery. 19. Ball screw transmission (10) according to claim 17, characterized in that the notches have substantially the same width over their length. 20. Ball screw drive (10) according to one of claims 17 to 19, characterized in that the at least one notch is connected at its radially inner end to the second gap (59, 79 ), the second gap substantially follows the direction of a circular arc or a circular chord and forms an angle of 20° to 60° when viewed outward from the center point (60, 80) of the support ring. 21. Ball screw transmission (10) according to claim 20, characterized in that the second gap (59, 79) has a non-constant width in its extension. 22. Ball screw drive (10) according to claim 20, characterized in that a block of material is defined by the notch, by the second gap (59, 79) and by the outer circumference of the support ring Extrusion elements (58, 78) are formed with elastic tongues (57, 77). 23. Ball screw transmission (10) according to claim 22, characterized in that the extrusion element (58, 78) has a radius with a positive deviation from the nominal outer diameter. 24. Ball screw drive (10) according to one of claims 16 to 19, characterized in that the bearing ring is formed in one piece from thermoplastic. 25. Ball screw drive (10) according to one of claims 16 to 19, characterized in that the spring element of the support ring additionally includes at least one pressing element (98) on the outer circumference. 26. Ball screw transmission (10) according to claim 25, characterized in that the at least one pressing element (98) of the support ring is made of a material that is more elastic than the remaining part of the support ring. material. 27. Ball screw transmission (10) according to claim 25, characterized in that the pressing element (98) has a radius with a positive deviation from the nominal outer diameter. 28. Ball screw transmission (10) according to claim 18, characterized in that the first gap has substantially the same width over its length. 29. The ball screw transmission device (10) according to claim 20, characterized in that the second gap substantially follows an arc or a chord when viewed outward from the center point (60, 80) of the support ring. trend and form an angle of 40° to 50°. 30. Ball screw drive (10) according to claim 21, characterized in that the end of the second slot facing away from the recess exhibits a substantially circular course of the slot wall.